Available Temperature units

• degree Celsius conversions

  Degree Celsius is a temperature unit based on the freezing and boiling points of water at standard atmospheric pressure. It is the most widely used scale for weather forecasting, cooking, and everyday temperature reporting worldwide.

• degree Fahrenheit conversions

  Degree Fahrenheit is a temperature unit primarily used in the United States for weather reports, cooking temperatures, and household settings. Water freezes at 32 °F and boils at 212 °F on this scale.

• kelvin conversions

  Kelvin is the SI base unit of thermodynamic temperature, with its zero point at absolute zero. It is the standard in scientific and engineering fields where absolute temperature values are required, such as thermodynamics and astrophysics.

• degree Rankine conversions

  Degree Rankine is an absolute temperature scale based on Fahrenheit-sized degrees, where zero is absolute zero. It is used in engineering thermodynamics in the United States, particularly in aerospace and mechanical engineering calculations.

• degree Réaumur conversions

  Degree Réaumur is a historical temperature scale where water freezes at 0° and boils at 80°. While largely obsolete, it was widely used in European science and medicine before the widespread adoption of Celsius.

Assumption: formula-based scales using Kelvin as reference.

Full Temperature conversion matrix

About Temperature

Temperature scales

Real-world uses

Temperature is fundamental to weather forecasting, cooking, industrial processes, and healthcare. HVAC systems regulate buildings using Celsius or Fahrenheit setpoints. Metallurgists monitor furnace temperatures in Kelvin or Celsius to control alloy properties. Medical thermometers detect fever with a precision of 0.1 °C. Food safety regulations specify holding temperatures to prevent bacterial growth, and semiconductor fabrication requires thermal control within fractions of a degree.

History

Daniel Fahrenheit introduced his mercury thermometer scale in 1724, setting 0 °F at the coldest temperature he could achieve with a salt-ice mixture. Anders Celsius proposed his centigrade scale in 1742, originally with 100° at freezing and 0° at boiling — later reversed. Lord Kelvin established the absolute temperature scale in 1848, anchoring 0 K at the theoretical point where all molecular motion ceases. The 2019 SI redefinition fixed the Boltzmann constant, tying the kelvin to fundamental physics.

Common mistakes

The most frequent error is applying a simple multiplication factor to convert between Celsius and Fahrenheit — the conversion requires both multiplication and an offset (°F = °C × 9/5 + 32). People also confuse Celsius degrees with kelvins when expressing temperature differences: a change of 1 °C equals a change of 1 K, but the scales have different zero points. Another mistake is using Rankine and Kelvin interchangeably; Rankine is the absolute scale corresponding to Fahrenheit, not Celsius.

Measurement standards

The kelvin is the SI base unit of thermodynamic temperature, defined by fixing the Boltzmann constant to exactly 1.380649 × 10⁻²³ joules per kelvin. This definition, adopted in 2019, decoupled the kelvin from the triple point of water.

Did you know?

The coldest temperature ever recorded on Earth was −89.2 °C (−128.6 °F) at the Soviet Vostok Station in Antarctica on 21 July 1983. In laboratories, scientists have cooled atoms to within billionths of a kelvin above absolute zero.

Common values